speak to union rep or not?

Ok, will try keep this short! My new HOD observed me during a mock ofsted this week. I went to pieces. Background - My dept suffered massive pressure last year and my lovely, capable HOD ended up standing down. I've struggled with my confidence since returning from maternity leave last year, with all the trouble going on thought it wise to keep this to myself and struggled through. I went to the doctors in sept and am on AD and awaiting counselling. I felt I was getting back to myself. I have some good friends in other depts that have supported me. I had being feeling positive about work again.Anyway, my new HOD observed me and really slated my handling of the class. (they are a difficult class, I've asked for support with behaviour management for them but not had any) I accept that things need to improve, and see it as an opportunity to get some help with them. However, when I tried to speak to new HOD about where we go from here, he made it clear that he now thinks that all my lessons are inadequate. (they are not! I've worked at the school for 13 years and have always had good results and being judged as being a good teacher) I got upset (tears of frustration!) and he became annoyed. He said " it was only a f**king lesson observation and I need to toughen up" that "I am not the biggest of his problems" and that I should "f*ck off home and get pissed or whatever I do to relax" I had gone in there wanting to explain myself but couldn't get a word in.I'm unsure what to do now. My friendly colleagues have said to speak to the union rep, but I don't want to make things worse with HOD. On the other hand, I found the way he spoke to me very offensive (and I'm not easily offended!) I love my job, and have resisted being signed off as my GP suggested. But, I have spent all weekend fretting about this and really don't want to go back and face him...

imho he sounds quite unprofessional out of order, not least with his language. Yes a convo with union rep would be a start, make it clear you need advice and support rather than interference action at this stage, but it may help to strengthen your case if you get it all on record now, iyswim. Don't let one crap lesson or one difficult class get you down